diff --git a/src/alignment/poa.rs b/src/alignment/poa.rs
index 4d90c3073..327cd76e1 100644
--- a/src/alignment/poa.rs
+++ b/src/alignment/poa.rs
@@ -5,6 +5,8 @@
 
 //! Partial-Order Alignment for fast alignment and consensus of multiple homologous sequences.
 //!
+//! - time complexity: `O(N^2 * L^2)`, where `N` is the number of sequences and `L` is the length of each sequence.
+//!
 //! For the original concept and theory, see:
 //! * Lee, Christopher, Catherine Grasso, and Mark F. Sharlow. "Multiple sequence alignment using
 //! partial order graphs." Bioinformatics 18.3 (2002): 452-464.