Douglas C. Werner resigned Monday as president...

Douglas C. Werner resigned Monday as president and chief executive of Western Health Plans Inc., the company said.

Western Health Plans would not comment on why Werner, who became president just nine months ago, resigned. Werner spent 13 years as a senior vice president with a large, national health-care company prior to joining Western Health Plans last year.

Executive Vice President Ray Mendoza will serve as chief executive until a permanent replacement is chosen, the company said.

The San Diego-based operator of health maintenance and health-care delivery organizations in California and Washington reported a $740,000 net loss and $89.9 million in revenue during 1986, compared to $8 million in net income and $68 million in revenue during 1985.

Company officials have described 1986 as “a year of consolidation” for Western Health Plans. Revenue increased by 28% to $89.9 million but costs also increased, largely because of expansion into new service areas, according to recent Securities and Exchange Commission filings.