Drugstore chain Walgreen ( WAG) announced Tuesday that its same-store sales rose 8.1% in May.

The company reported that May total sales increased 12.3% to $2.81 billion, compared with $2.51 billion in the same month last year. May pharmacy sales climbed 14.6%, while comparable pharmacy sales rose 10.9%.

Sales for the nine months of the fiscal year-to-date rose 13.1% from the same time period in 2002, reaching $24.26 billion, vs. last year's $21.45 billion. Comparable-store sales for the fiscal year-to-date grew 8.1%.

On May 31, the company operated 4,050 drugstores in 43 states and Puerto Rico, up from 3,766 a year ago, according to a statement released by the company. Walgreen's shares were up 4.6%, or $1.42, to $32.11 in midday New York Stock Exchange trading.