KKRZ (100.3 MHz) is a commercial FM radio station in Portland, Oregon, known as Z100. It is owned by iHeartMedia and airs a contemporary hit radio (CHR) format. The studios and offices are on SW 68th Parkway in Tigard.

KKRZ has an effective radiated power (ERP) of 100,000 watts, the maximum for most U.S. FM stations. Its transmitter site is in Portland's West Hills, off NW Skyline Boulevard.

KKRZ also transmits using HD Radio technology. Its HD2 digital subchannel carries an alternative rock format known as "Alt 102.3." That signal feeds the 99-watt FM translator K272EL on 102.3 MHz.

Z100 carries a pair of syndicated shows on weekdays, "Johnjay and Rich" in morning drive time and Ryan Seacrest at midday. Local DJs are heard in the afternoon and evening.

In addition to the morning show, KKRZ's weekday lineup includes On Air with Ryan Seacrest in middays, Maui in early afternoons, Zann in afternoon drive time, and Jake B. in the evening. Other personalities include Kayla, Sos and Matt Holiday. Weekends feature American Top 40 with Ryan Seacrest, the iHeartRadio Countdown, On The Move with Enrique Santos, Most Requested Live with Romeo and The Vibe with Tanya and EJ. Weather reports are provided by ABC affiliate KATU, and traffic reports are supplied by sister station KEX.

Technically there have been two separate Portland stations operating at FM 100.3. The original KGW-FM began broadcasting at 4:50 p.m. on May 7, 1946, as the first FM station in Oregon. KGW-FM initially broadcast on 95.3 MHz, and moved to 100.3 MHz on September 22, 1947. KGW-AM-FM were both owned by Portland's daily newspaper, The Oregonian. KGW-FM mostly simulcast its AM counterpart, which was affiliated with the NBC Red Network, carrying its dramas, comedies, news, sports, soap operas, game shows and big band broadcasts during the "Golden Age of Radio".

The original KGW-FM ceased broadcasting on February 1, 1950, and returned its license to the Federal Communications Commission (FCC) for cancellation. An offer to donate its transmitter to the Portland School Board, which had operated an AM station, KBPS, since 1923, was turned down, because "too much expense would be involved in conversion of present AM receivers in the schools". KGW-FM's demise raised doubts about FM's future, as one reviewer asked: "Is KGW, which led Portland stations' parade into FM, leading a parade back out? Are FM set owners eventually to be tuned in only to static-free silence?"

In late 1950, ownership of KGW (AM) was transferred to Pioneer Broadcasters, Inc. On August 17, 1951, the FCC received an application from Pioneer Broadcasters for what was technically a new FM station, transmitting on the vacated 100.3 MHz frequency. The applicants were quoted that "As far as we know we are the first licensee to reapply for permission to operate FM facilities", however, "we believe that there is a definite future for FM operation". Although the revived station initially received the call sign KGW-FM, and transmitted on the same frequency used by the original station, FCC records treated this as a new operation, separate from the 1946-1950 version. However, station histories have traditionally treated this as a continuation of the original KGW-FM.