Three of the country's largest educational publishers all reported gains in sales and profits for the third quarter ended September 30, 1999.

The largest increase was posted by McGraw-Hill Cos.'educational and professional book publishing subsidiary, where sales in the group rose 7.5% to $766.5 million, while operating income was up 27.8% to $235.1 million. Excluding the $16 million write-down taken in last year's third quarter for its Continuing Education Center, profits were up 17.6% in the most recent period.

According to MHC, all the units in its school group--elementary, secondary, supplementary and testing--posted gains in the quarter. Sales in the professional book group's medical unit had "excellent" results, helped by the recent acquisition of Appleton & Lange. Sales of computer titles were also up, with sales through online retailers continuing to grow rapidly. International operations also had a gain in the quarter; good performances in Canada, Mexico and the Asia-Pacific region offset weakness in Latin America and Spain.

For the first nine months of the year, operating profits for the entire group rose 29.4% to $232.5 million, on a 5.6% revenue gain to $1.35 billion.

At Tribune Co., revenues in its education division rose 6% in the quarter to $199 million, while operating profits increased 11% to $32 million. Tribune cited strong sales in math and language arts as the primary reason for the improvement. For the nine-month period, operating profit was up 10% to $45.5 million on a 7% sales increase to $276.8 million.

Houghton Mifflin said that slower than expected sales in its K-12 group kept its overall sales increase to 2.4%, with revenues hitting $457.8 million in the quarter. Income from operations was up 5.6% to $93.6 million. Fewer adoption opportunities in reading and language arts limited growth in HM's K-12 publishing group to 0.9% with sales reaching $342 million. Sales in the college division rose 9% to $87.1 million, while revenues in the "other" segment increased 2.3% to $28.7 million with the gain due entirely to improvements in the trade & reference division.

For the nine-month period, income from operations rose 10% to $65 million on a 5.8% sales gain to $763 million.