The IBM Thinkpad 350 series was a notebook computer series introduced in 1993 by IBM as part of their Thinkpad laptop series. It was the successor to the IBM ThinkPad 300. With only 2 models ever made in the series, it was succeeded in 1994 by the IBM Thinkpad 360 series.

The 350 was announced in June 1993. The 125MB disk version started shipping in June 1993, the 250MB version started shipping in July.

The New York Times noted that IBM challenged Compaq with the development of the 350, who was the market leader in the lower priced notebook market.

The 350 series shipped with IBM PC DOS 5.02 as the included operating system.

Both models in the series came with an Intel 486SL running at 25 MHz, and a CT-65530 video controller with 1 MB of video memory. Both models also had a standard 4 MB of RAM that was on a proprietary IC DRAM Card. If a user wanted to upgrade the ram, the 350 ThinkPads supported an IC DRAM Card size up to 20 MB.

Both in the series came with a 125 or 250 MB standard hard drive, and a non-removable 1.44 MB floppy drive. Both models also had a battery life up to 9 hours.

In March 1994, IBM cut the prices by 12%.

The 350 is identical to the PS/Note 425 and the 350C is identical to the PS/Note 425C.