HH may refer to:
The h/h blood group, also known as Oh or the Bombay blood group, is a rare blood type. This blood phenotype was first discovered in Bombay, now known as Mumbai, in India, by Dr. Y. M.
The HH Ferry route (About the name: Helsingør–Helsingborg; Helsingør is Danish for Elsinore) is a very old shipping route which connects Helsingør on Zealand, Denmark and Helsingborg, Scania, Sweden across the northern, and narrowest part of the Øresund.
Human Herpes Virus (HHV) Infected Cell Polypeptide 0 (ICP0) is a protein, encoded by the DNA of herpes viruses.
HHL Leipzig Graduate School of Management, formerly known as Handelshochschule Leipzig, is a private business school based in Saxony, Germany.
HipHop Virtual Machine (HHVM) is an open-source virtual machine based on just-in-time (JIT) compilation that serves as an execution engine for the Hack programming language and used to support PHP execution before the release of HHVM version 4. By using the principle of JIT compilation, Hack code is first transformed into intermediate HipHop bytecode (HHBC), which is then dynamically translated into x86-64 machine code, optimized, and natively executed.
The HH-suite is an open-source software package for sensitive protein sequence searching. It contains programs that can search for similar protein sequences in protein sequence databases.