The MicroVAX is a discontinued family of low-cost minicomputers developed and manufactured by Digital Equipment Corporation (DEC). The first model, the MicroVAX I, shipped in 1984. The series uses processors that implement the VAX instruction set architecture (ISA) and were succeeded by the VAX 4000. Many members of the MicroVAX family have corresponding VAXstation variants, which primarily differ by the addition of graphics hardware. The MicroVAX family supports Digital's VMS, ULTRIX, and VAXELN operating systems. Prior to VMS V5.0, MicroVAX hardware required a dedicated version of VMS named MicroVMS.

The MicroVAX I, code-named Seahorse, introduced in October 1984, was one of DEC's first VAX computers to use very-large-scale integration (VLSI) technology. The KA610 CPU module (also known as the KD32) contains two custom chips which implemented the ALU and FPU while TTL chips were used for everything else. Two variants of the floating point chips are supported, with the chips differing by the type of floating-point instructions supported, F and G, or F and D. The system was implemented on two quad-height Q-bus cards, a Data Path Module (DAP) and Memory Controller (MCT). The MicroVAX I uses Q-bus memory cards, which limits the maximum memory to 4MiB. The performance of the MicroVAX I is rated at 0.3 VUPs, equivalent to the earlier VAX-11/730.

The MicroVAX II, code-named Mayflower, is a mid-range MicroVAX introduced in May 1985 and shipped shortly thereafter. It replaced the original MicroVAX in DEC's product line; the company offered a field upgrade to existing customers. MicroVAX II runs VAX/VMS or, alternatively, ULTRIX, DEC's Unix operating system. At least one non-DEC commercial operating system was available, BSD Unix from mt Xinu.

MicroVAX II was designed to provide 70-110% of VAX-11/780 performance at a lower price. It runs all VAX software but is not compatible with all peripherals, and at launch was not capable of VAXclustering. As DEC did not adjust prices for older computers, Forrester Research predicted that customers would prefer MicroVAX II to VAX-11/725, 730, and possibly 750. It uses the KA630-AA CPU module, a quad-height Q22-Bus module, with a MicroVAX 78032 microprocessor and a MicroVAX 78132 floating-point coprocessor operating at 5 MHz (200 ns cycle time). Two gate arrays on the module implement the external interface for the microprocessor, Q22-bus interface and the scatter-gather map for DMA transfers over the Q22-Bus. The module also contains 1 MB of memory, an interval timer, two ROMs for the boot and diagnostic facility, a DZ console serial line unit, and a time-of-year clock. A 50-pin connector for a ribbon cable near the top left corner of the module provides the means by which more memory is added to the system.

The minicomputer supports 1 to 16 MB of memory through zero, one or two memory expansion modules. The MS630 memory expansion module is used for expanding memory capacity. Four variants of the MS630 exists: the 1 MB MS630-AA, 2 MB MS630-BA, 4 MB MS630-BB and the 8MB MS630-CA. The MS630-AA is a dual-height module, whereas the MS630-BA, MS630-BB, and MS630-CA are quad-height modules. These modules use 256 Kb DRAMs and are protected by byte-parity, with the parity logic located on the module. The modules connect to the CPU module via the backplane through the C and D rows and a 50-conductor ribbon cable. The backplane serves as the address bus and the ribbon cable as the data bus.

The MicroVAX II came in three models of enclosure:

DEC at the same time also announced the VAXstation II, a workstation based on MicroVAX II's CPU and also replacing the original VAXstation.

The Robotron K 1820 is a copy of the MicroVAX II developed in the GDR and was produced for a short period of time in 1990.