Exhibit 11 WASTE INDUSTRIES, INC. COMPUTATION RE: EARNINGS PER SHARE Pro forma (1) Three Months Ended March 31, 1998 1999 ---- ---- Net income $ 2,353,751 $ 2,851,606 ============ ============ Weighted average number of common shares issued and outstanding - Basic 12,651,701 13,501,905 Incremental shares under stock option plans 385,980 357,608 ------------ ------------ Weighted average shares outstanding - Diluted 13,037,681 13,859,513 ------------ ------------ Basic earnings per share $ 0.19 $ 0.21 ============ ============ Diluted earnings per share $ 0.18 $ 0.21 ============ ============ (1) Pro forma basic and diluted earnings per share computations are based on the weighted-average common stock outstanding and include the dilutive effect of stock options using the treasury stock method. Common stock outstanding used to compute the weighted-average shares was retroactively adjusted for the acquisition of entities under common control during the quarter ended March 31, 1998, and for the merger with entities under the pooling of interest method during 1998. 14