A variation on Tomita’s algorithm is analyzed in regards to its time and space complexity. It is shown to have a general time bound of 0(n ^̃𝜌+1), where n is the length of the input string and 𝜌 is the length of the longest production. A modified algorithm is presented in which the time bound is reduced to 0(n³). The space complexity of Tomita’s algorithm is shown to be proportional to n² in the worst case and is changed by at most a constant factor with the modification. Empirical results are used to illustrate the trade off between time and space on a simple example. A discussion of two subclasses of context-free grammars that can be recognized in 0(n²) and O(n) is also included.