| Election Name: | 1998 California State Senate election |
| Country: | California |
| Type: | legislative |
| Ongoing: | no |
| Previous Election: | 1996 California State Senate election |
| Previous Year: | 1996 |
| Next Election: | 2000 California State Senate election |
| Next Year: | 2000 |
| Seats For Election: | 20 seats from even-numbered districts in the California State Senate |
| Majority Seats: | 21 |
| Leader1: | John Burton |
| Party1: | California Democratic Party |
| Leaders Seat1: | 3rd–San Francisco |
| Seats Before1: | 23 |
| Seats After1: | 25 |
| Seat Change1: | 2 |
| Popular Vote1: | 1,975,326 |
| Percentage1: | 56.49% |
| Leader2: | Ross Johnson |
| Party2: | California Republican Party |
| Leaders Seat2: | 35th–Fullerton |
| Seats Before2: | 16 |
| Seats After2: | 15 |
| Seat Change2: | 1 |
| Popular Vote2: | 1,426,014 |
| Percentage2: | 40.78% |
| Map Size: | 450px |
| President pro tempore | |
| Posttitle: | President pro tempore-designate |
| Before Election: | John L. Burton |
| Before Party: | California Democratic Party |
| After Election: | John L. Burton |
| After Party: | California Democratic Party |
The 1998 California State Senate elections were held on November 3, 1998. Senate seats of even-numbered districts were up for election. Senate terms are staggered so that half the membership is elected every two years. Senators serve four-year terms and are limited to two terms. Democrats expanded their majority, winning a Republican-held seat and an Independent-held seat.
| California State Senate elections, 1998 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Party | Votes | Percentage | Not up | Incumbents | Open | Before | After | +/– | ||
| Democratic | 1,975,326 | 56.49% | 10 | 5 | 8 | 23 | 25 | +2 | ||
| Republican | 1,426,014 | 40.78% | 10 | 3 | 3 | 16 | 15 | -1 | ||
| Libertarian | 57,738 | 1.65% | 0 | 0 | 0 | 0 | 0 | 0 | ||
| Peace and Freedom | 26,277 | 0.75% | 0 | 0 | 0 | 0 | 0 | 0 | ||
| Natural Law | 5,828 | 0.17% | 0 | 0 | 0 | 0 | 0 | 0 | ||
| Independent | 5,504 | 0.16% | 0 | 0 | 1 | 1 | 0 | -1 | ||
| Invalid or blank votes | 342,926 | 8.93% | — | — | — | — | — | — | ||
| Totals | 3,839,613 | 100.00% | 20 | 8 | 12 | 40 | 40 | — | ||
Final results from the California Secretary of State:[1]
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